1. Technical Field
The present disclosure generally relates to illuminating devices, particularly, to an illuminating device having improved utilization rate.
2. Discussion of Related Art
With the continuing development of scientific technology, light emitting diodes (LEDs) have been widely used in illumination devices to substitute for conventional cold cathode fluorescent lamps (CCFL) due to their high brightness, long life-span, and wide color gamut.
Conventional illuminating devices incorporating LEDs generally generate butterfly-type light fields or diffusion-type light fields. Referring to FIG. 9, a diffusion-type light field is shown. The diffusion-type light field is substantially circular. In other words, a part of the light field along an x-direction is substantially the same as a part of the light field along a y-direction. However, this type of light field is not a good fit for street lights, which usually requires a strip-type light field. If the diffusion-type light field is applied in the street lamp, part of light will be lost, which decreases utilization rate of the light emitted from the LEDs.
What is needed, therefore, is an illuminating device which can improve utilization rate of the light emitted from LEDs.